Urophysa is a Chinese endemic genus comprising two species, Urophysa rockii and Urophysa henryi. In this study, we sequenced the complete chloroplast (cp) genomes of these two species and of their relative Semiquilegia adoxoides. Illumina sequencing technology was used to compare sequences, elucidate the intra- and interspecies variations, and infer the phylogeny relationship with other Ranunculaceae family species. A typical quadripartite structure was detected, with a genome size from 158,473 to 158,512 bp, consisting of a pair of inverted repeats separated by a small single-copy region and a large single-copy region. We analyzed the nucleotide diversity and repeated sequences components and conducted a positive selection analysis by the codon-based substitution on single-copy coding sequence (CDS). Seven regions were found to possess relatively high nucleotide diversity, and numerous variable repeats and simple sequence repeats (SSR) markers were detected. Six single-copy genes (atpA, rpl20, psaA, atpB, ndhI, and rbcL) resulted to have high posterior probabilities of codon sites in the positive selection analysis, which means that the six genes may be under a great selection pressure. The visualization results of the six genes showed that the amino acid properties across each column of all species are variable in different genera. All these regions with high nucleotide diversity, abundant repeats, and under positive selection will provide potential plastid markers for further taxonomic, phylogenetic, and population genetics studies in Urophysa and its relatives. Phylogenetic analyses based on the 79 single-copy genes, the whole complete genome sequences, and all CDS sequences showed same topologies with high support, and U. rockii was closely clustered with U. henryi within the Urophysa genus, with S. adoxoides as their closest relative. Therefore, the complete cp genomes in Urophysa species provide interesting insights and valuable information that can be used to identify related species and reconstruct their phylogeny.

Fritillaria is a genus that has important medicinal and horticultural values. The study involved the most comprehensive chloroplast genome samples referring to Old and New World clades of Fritillaria for marker selection and phylogenetic studies. We reported and compared eleven newly sequenced whole-plastome sequences of Fritillaria which proved highly similar in overall size (151,652–152,434 bp), genome structure, gene content, and order. Comparing them with other species of Liliales (6 out of 10 families) indicated the same similarity but showed some structural variations due to the contraction or expansion of the inverted repeat (IR) regions. A/T mononucleotides, palindromic, and forward repeats were the most common types. Six hypervariable regions (rps16-trnQ, rbcL-accD, accD-psaI, psaJ-rpl33, petD-rpoA, and rpl32-trnL) were discovered based on 26 Fritillaria whole-plastomes to be potential molecular markers. Based on the plastome data that were collected from 26 Fritillaria and 21 Lilium species, a phylogenomic study was carried out with three Cardiocrinum species as outgroups. Fritillaria was sister to Lilium with a high support value, and the interspecies relationships within subgenus Fritillaria were resolved very well. The six hypervariable regions can be used as candidate DNA barcodes of Fritillaria and the phylogenomic framework can guide extensive genomic sampling for further phylogenetic analyses.

Bupleurum L. (Apiaceae) is a perennial and herbal genus, most species of which have high medicinal value. However, few studies have been performed using plastome data in this genus, and the phylogenetic relationships have always been controversial. In this study, the plastid genomes of Bupleurum chinense and Bupleurum commelynoideum were sequenced, and their gene content, order, and structure were counted and analyzed. The only three published Bupleurum species (B. boissieuanum, B. falcatum, and B. latissimum) and other fifteen allied species were selected to conduct a series of comparative and phylogenetic analyses. The genomes of B. chinense and B. commelynoideum were 155,869 and 155,629 bp in length, respectively, both of which had a typical quadripartite structure. The genome length, structure, guanine and cytosine (GC) content, and gene distribution were highly similar to the other three Bupleurum species. The five Bupleurum species had nearly the same codon usages, and eight regions (petN-psbM, rbcL-accD, ccsA-ndhD, trnK(UUU)-rps16, rpl32-trnL(UAG)-ccsA, petA-psbJ, ndhF-rpl32, and trnP(UGG)-psaJ-rpl33) were found to possess relatively higher nucleotide diversity, which may be the promising DNA barcodes in Bupleurum. Phylogenetic analysis revealed that all Bupleurum species clustered into a monophyletic clade with high bootstrap support and diverged after the Chamaesium clade. Overall, our study provides new insights into DNA barcoding and phylogenetic relationship between Bupleurum and its related genera, and will facilitate the population genomics, conservation genetics, and phylogenetics of Bupleurum in Apiaceae.

With the development of molecular sequencing approaches, many taxonomic and phylogenetic problems of the genus Allium L. have been solved; however, the phylogenetic relationships of some subgenera or sections, such as section Bromatorrhiza, remain unresolved, which has greatly impeded our full understanding of the species relationships among the major clades of Allium. In this study, the complete chloroplast (cp) genomes of nine species in the Allium sect. Bromatorrhiza were determined using the Illumina paired-end sequencing, the NOVOPlasty de novo assembly strategy, and the PGA annotation method. The results showed that the cp genome exhibited high conservation and revealed a typical circular tetrad structure. Among the sect. Bromatorrhiza species, the gene content, SSRs, codon usage, and RNA editing site were similar. The genome structure and IR regions’ fluctuation were investigated while genes, CDSs, and non-coding regions were extracted for phylogeny reconstruction. Evolutionary rates (Ka/Ks values) were calculated, and positive selection analysis was further performed using the branch-site model. Five hypervariable regions were identified as candidate molecular markers for species authentication. A clear relationship among the sect. Bromatorrhiza species were detected based on concatenated genes and CDSs, respectively, which suggested that sect. Bromatorrhiza is monophyly. In addition, there were three genes with higher Ka/Ks values (rps2, ycf1, and ycf2), and four genes (rpoC2, atpF, atpI, and rpl14) were further revealed to own positive selected sites. These results provide new insights into the plastome component, phylogeny, and evolution of Allium species.

Urophysa is a Chinese endemic genus with only two species (U. rockii and U. henryi) distributed in Yungui Plateau (Guizhou Province) and adjacent regions (i.e., Provinces of Hunan, Hubei, Chongqing and Sichuan). The aim of this study was to determine the genetic diversity and population differentiation within Urophysa and investigate the effect of the Yungui Plateau uplift and climate oscillations on evolution of Urophysa. In this study, micro-morphological characteristics, nine microsatellite loci (SSR), two nuclear loci (ITS and ETS) and two chloroplast fragments (psbA-trnH and trnL-trnF) were used to analyze the phylogenetic relationships and assess genetic and phylogeographical structure of Urophysa. Isolation by distance (IBD) was performed to research the effects of geographical isolation. We detected high genetic diversity at the species level but low genetic diversity within populations. Striking genetic differentiation (AMOVA) among populations and a significant phylogeographical structure (N_ST > G_ST, p < 0.01) were detected among U. henryi populations, along with significant effects of isolation by distance (IBD). Molecular clock estimation using calibration strategy and cpDNA substitution rate indicated that the divergence of U. henryi occurred during late Miocene to early Quaternary, when the orogeny of Yungui Plateau was violent. U. rockii originated at the early Quaternary and further differentiated at early Pleistocene. Our results suggested that habitat fragmentation played an important role in the genetic diversity and population differentiation of U. rockii and U. henryi. Heterogenous geomorphological configuration and complicated environment resulted from rapid uplift of the Yungui Plateau were inferred as important incentives for the modern phylogeograhpical pattern and species divergence of Urophysa. The geographical isolation, limited gene flow, specialized morphologies and the Pleistocene climatic oscillation greatly contributed to the allopatric divergence of U. rockii. Significant genetic drift and inbreeding were detected in these two species, in situ measures should be implemented to protect them.

Peucedanum franchetii is a famous folk medicinal plant in China. However, the taxonomy of the P. franchetii has not been sufficiently resolved. Due to similar morphological features between P. franchetii and Ligusticopsis members, the World Flora Online (WFO) Plant List suggested that this species transformed into the genus Ligusticopsis and merged with Ligusticopsis likiangensis. However, both species are obviously diverse in leaf shape, bracts, and bracteoles. To check the taxonomic position of P. franchetii, we newly sequenced and assembled the plastome of P. franchetii and compared it with nine other plastomes of the genus Ligusticopsis. Ten plastomes were highly conserved and similar in gene order, codon bias, RNA editing sites, IR borders, and SSRs. Nevertheless, 10 mutation hotspot regions (infA, rps8, matK, ndhF, rps15, psbA-trnH, rps2-rpoC2, psbA-trnK, ycf2-trnL, and ccsA-ndhD) were still detected. In addition, both phylogenetic analyses based on plastome data and ITS sequences robustly supported that P. franchetii was not clustered with members of Peucedanum but nested in Ligusticopsis. P. franchetii was sister to L. likiangensis in the ITS topology but clustered with L. capillacea in the plastome tree. These findings implied that P. franchetii should be transferred to genus Ligusticopsis and not merged with L. likiangensis, but as an independent species, which was further verified by morphological evidences. Therefore, transferring P. franchetii under the genus Ligusticopsis as an independent species was reasonable, and a new combination was presented.